Table of Contents

• What is LRTK Phone accuracy? Centimeter-level positioning achievable with a smartphone

• Accuracy and challenges of conventional smartphone AR point cloud scans

• How LRTK Phone improves accuracy

• Comparison with professional surveying equipment: the capability of LRTK Phone accuracy

• Possibilities opened by higher-accuracy smartphone point cloud scanning

• What “simple surveying” enabled by LRTK looks like

• Conclusion

• FAQ

What is LRTK Phone accuracy? Centimeter-level positioning achievable with a smartphone

LRTK Phone is a revolutionary system that enables centimeter-level positioning (cm level accuracy (half-inch accuracy)) using only a smartphone (especially an iPhone). Normally, smartphone GPS positioning accuracy is said to be on the order of several meters, but with LRTK Phone you can determine positions with survey-equipment-level accuracy of only a few centimeters of error. This is achieved by a dedicated ultra-compact GNSS receiver that leverages the positioning technique called RTK (Real-Time Kinematic), a smartphone app, and a cloud service. Simply attach the small device that fits in your pocket to your smartphone, and you can obtain position information with accuracy comparable to expensive surveying equipment.

With this “cm level accuracy (cm level accuracy (half-inch accuracy))” positioning, any data acquired with a smartphone can be tagged with precise coordinates. For example, if you scan the surroundings with an iPhone’s built-in LiDAR sensor or AR features, you can assign latitude, longitude, and elevation in a global coordinate system to the acquired point cloud. Before LRTK Phone, point clouds scanned with a smartphone only had relative coordinates, and aligning them to actual site coordinates required additional adjustment. By using LRTK Phone’s high-precision position information, smartphone AR point cloud scans can be given absolute (global) coordinates, enabling 3D data acquisition with scale and spatial relationships that match the site exactly.

Accuracy and challenges of conventional smartphone AR point cloud scans

3D scanning using smartphone AR technology has attracted attention as an easy way to acquire on-site three-dimensional data. However, conventional smartphone AR point cloud scanning has had several accuracy-related challenges. Specifically, the following issues have been problematic:

• GPS accuracy limits: Typical built-in smartphone GPS commonly has errors on the order of several meters, which is insufficient for wide-area surveying or precise alignment. Even just plotting on a map can show meter-level offsets, making it difficult to use for accurate position records.

• Accumulation of AR scan errors: Smartphone AR scans (e.g., iPhone LiDAR scans) acquire point clouds while estimating the device’s pose using the device’s IMU sensors and camera. Therefore, as travel distance increases, errors gradually accumulate, causing distortions or scale shifts in the scanned 3D model. In some cases, errors of a few percent in length or height can occur, which is problematic when precision is required.

• Lack of absolute coordinates: Scan data from a smartphone alone is basically recorded in a local coordinate system (relative coordinates for that session). When overlaying with other surveying data or design drawings later, manual transformation and alignment based on control points are required, which is time-consuming. Especially for surveying purposes, the inability to acquire data in an absolute coordinate system such as a national geodetic coordinate system was a major limitation.

As described above, the convenience of smartphone AR point cloud scanning comes with accuracy limits, and the conventional wisdom has been that “it’s usable for simple records and visualization, but difficult for precise surveying.”

How LRTK Phone improves accuracy

LRTK Phone’s technology solves these issues and dramatically improves the accuracy of smartphone AR point cloud scans. Let’s look at how LRTK Phone achieves high accuracy.

• Centimeter positioning via RTK-GNSS: LRTK Phone includes a high-performance GNSS receiver that acquires signals not only from GPS but from multiple satellite positioning systems (GNSS). It also receives real-time correction information from a base station using RTK, which greatly reduces positioning errors. As a result, under open-sky conditions LRTK Phone reaches a “Fix” (fixed solution) in about 20–40 seconds and can determine the smartphone’s position with astonishing accuracy of about horizontal ±2 cm (±0.8 in) and vertical ±4 cm (±1.6 in). Whereas conventional smartphone GPS had accuracy around ±10 m (±32.8 ft), RTK makes accuracy hundreds of times better.

• Integration with the smartphone’s AR functions: The high-precision position information from LRTK Phone is integrated into the smartphone’s AR engine (for example, iPhone ARKit). This allows the smartphone to always maintain an accurate pose in the real world as it moves through space. Normal AR scans suffer from some pose-estimation error, but by adding LRTK’s correction data, device tracking becomes more accurate and distortions or scale shifts in point cloud data are greatly reduced. In other words, each point captured by the smartphone camera or LiDAR is mapped in real time to the correct geographic coordinates.

• Acquisition of point clouds with absolute coordinates: Thanks to high-precision positioning and AR integration, point clouds scanned with a smartphone are recorded from the start with absolute coordinates (such as a geodetic reference). This means you can obtain 3D data that can be used as surveying results on site without special calibration work. For example, when scanning terrain or structures, the point cloud data can be immediately overlaid on maps or CAD design data, greatly improving post-processing efficiency. In addition, the acquired point cloud can be checked on the smartphone in real time, and any missing areas can be rescanned as needed, allowing on-site quality checks while acquiring data.

• Dedicated app and cloud service: The LRTK Phone system includes a dedicated iPhone app and a cloud service (LRTK Cloud) for data management and processing. The app has an intuitive UI that provides one-stop operation from starting positioning to point cloud scanning and AR display. On the cloud you can view uploaded point cloud data on a 3D map, measure distances, areas, and volumes, and compare with design models. This software support enables immediate utilization of high-precision data acquired on site.

Through this hardware-software integration, LRTK Phone dramatically improves both the accuracy and practicality of smartphone AR point cloud scanning.

Comparison with professional surveying equipment: the capability of LRTK Phone accuracy

You may wonder, “Even if it’s theoretically high-precision, can a smartphone really measure that accurately?” Let’s verify LRTK Phone’s accuracy by comparing it to professional surveying equipment.

According to in-house and field validations, coordinates obtained with LRTK Phone were found to be comparable to those from a Class 1 GNSS receiver (survey-grade GPS) used by professional surveyors. Specifically, the same point was measured with both LRTK Phone and a Class 1 GNSS receiver, and the coordinates were compared. The coordinate differences between the two were on the order of a few millimeters (in all cases less than 5 mm (<0.20 in)) in both horizontal and vertical directions, staying within a few millimeters. This indicates that despite being a small device attached to a smartphone, LRTK Phone achieves sub-centimeter-level accuracy comparable to professional surveying equipment.

In another validation, the coordinates of known points were measured dozens of times with LRTK Phone, and the mean and variance were analyzed to evaluate stability. The variation between measurements was very small, and the mean values were extremely close to theoretical values, demonstrating consistently high reproducibility. This shows that LRTK Phone does not just produce a single accidental high-precision result; it maintains high accuracy even with repeated measurements.

Importantly, this level of accuracy can be obtained easily in the field. Traditionally, achieving centimeter positioning required large GNSS equipment mounted on tripods or total stations operated by specialized surveyors. LRTK Phone, being smartphone-sized and operable with one hand, brings down the barrier to on-site surveying work. High accuracy combined with ease of use is LRTK Phone’s greatest strength.

Possibilities opened by higher-accuracy smartphone point cloud scanning

With LRTK Phone dramatically improving smartphone AR point cloud scan accuracy, various applications that were previously difficult become realistic. Here are some possibilities enabled by higher accuracy.

First, utilization in civil engineering and construction sites is notable. Tasks that used to require surveying equipment, such as as-built measurements and pre-/post-earthwork terrain surveys, can now be completed simply by walking the site with a smartphone equipped with LRTK Phone and scanning point clouds. For example, even when calculating the volume of large embankments or excavation areas, accurate volume computation is possible from smartphone-scanned point clouds. Because the point clouds have absolute coordinates, they can be immediately compared with design cross-sections or reference heights to decide how much material to add or remove on the spot. LRTK Phone is ideal for routine quality-control measurements. Tasks that previously required outsourcing to specialists can be performed frequently by in-house staff, greatly improving the speed and accuracy of progress management and quality checks.

Next, possibilities expand for infrastructure inspection and disaster sites. Because high-precision 3D point clouds can be obtained easily, smartphones can be used for displacement measurement of bridges and tunnels, or for assessing slope collapse conditions. For example, immediately after a disaster, a smartphone with LRTK Phone can acquire detailed 3D data of hazardous sites in a short time without survey teams having to spend long periods in danger. Data can be shared via the cloud instantly, allowing the office or remote experts to collaborate in real time and develop rapid response plans. The ability to complete initial surveying and documentation with a single smartphone is a major advantage.

Furthermore, combining with AR technology creates new developments. With lower accuracy, overlaying virtual design models on site suffered from large misalignments, but LRTK Phone makes it possible to display BIM/CIM models precisely aligned with the real world. This enables checking full-scale, accurately positioned completion images on site that previously existed only in design drawings or 3D models. Applications such as AR visualization of design proposals or AR display of buried utilities to assist excavation become feasible. Accurate AR helps reduce construction errors and facilitates sharing design intent on site, making it a key technology for construction DX (digital transformation).

Thus, improving smartphone AR point cloud scan accuracy is not just a technological upgrade; it has the potential to transform on-site workflows. Affordable and easy-to-use tools enabling high-quality 3D data for everyone make tasks once left to specialists executable by site teams, speeding decision-making and reducing costs.

What “simple surveying” enabled by LRTK looks like

LRTK Phone is not only for smartphone point cloud scanning; it is also a trump card for “simple surveying” that makes all kinds of on-site measurements easy. Traditionally, surveying required specialized equipment and advanced skills, but with LRTK, field staff can complete small measurements by themselves on the spot.

Here are the main functions available with simple surveying using LRTK:

• One-touch point measurement: With LRTK Phone attached to your smartphone, you can record the coordinates of a specific point with a single tap. If the positioning state is Fix, the acquired coordinates for latitude, longitude, and elevation are accurate to within a few centimeters. For example, boundary points or arbitrary feature locations can be measured accurately by a single person approaching and tapping.

• Distance and area measurement without a tape measure: The dedicated app can immediately calculate distances between two points or the area enclosed by a polygon using on-site point clouds or photos. There is no need to pull a tape or use a surveying calculator. Tap the required points on the smartphone screen and high-accuracy lengths and areas are computed automatically.

• Immediate volume and earthwork calculation: You can calculate the volume of embankments or excavations from point cloud data on the spot. For instance, when needing to know the amount of earth moved, scan around the site with your smartphone, upload to the cloud, and the accurate soil volume will be computed in a short time. This allows immediate decisions for truck dispatch or soil disposal planning.

• Stakeout and position guidance: The LRTK app includes a “coordinate guidance (stakeout)” function that guides the user to a specified coordinate. As you approach a pre-set target point, the remaining distance is displayed on the screen in centimeter units, and you are notified when you reach the correct spot. Using this, operations that previously required two people—like stakeout with a total station—can be performed by one person using a smartphone. With AR display, you can also show a flag or marker 3D model at the target point to provide visual guidance.

• Geotagged photo records: Photos taken with the smartphone can be tagged with high-precision position coordinates and orientation information. When reviewing photos later, you can know exactly where and in which direction each was taken, which is useful for reporting and time-series comparisons. The cloud also supports plotting photos on a map so shooting locations are immediately visible.

As described, the LRTK-based system centered on LRTK Phone makes surveying and measurement tasks that used to require specialists or expensive equipment surprisingly accessible. “Measure on the spot whenever you think of it” becomes a reality, accelerating decision-making and increasing site autonomy. LRTK presents a modern approach to simple surveying that fits today’s job sites.

Conclusion

We have examined in detail LRTK Phone accuracy, which revolutionizes smartphone AR point cloud scanning, from its mechanics to use cases. The significance of achieving centimeter-level positioning with a smartphone and immediately assigning absolute coordinates to point clouds cannot be overstated. LRTK Phone transforms the smartphone from a mere gadget into a full-fledged surveying tool, accelerating on-site digitization and efficiency.

The combination of high accuracy and ease of use offered by LRTK Phone creates new opportunities not only for surveying and construction management but for all scenarios that utilize spatial data. From precise point cloud scanning to simple surveying and AR visualization, tasks that were previously performed separately can now be seamlessly connected with a single smartphone. If your work involves “wanting easier access to accurate on-site data” or “pushing forward DX,” the option of smartphone surveying with LRTK is well worth considering. Experience the cutting-edge LRTK Phone accuracy for yourself.

FAQ

Q: What does LRTK Phone stand for?

A: “LRTK” is the name of our solution and refers to a high-precision positioning system that utilizes RTK (Real-Time Kinematic) technology. “Phone” indicates that it works in conjunction with a smartphone, and together we call it LRTK Phone. The difference from typical GPS is that real-time correction information dramatically improves positioning accuracy.

Q: What positioning accuracy can LRTK Phone achieve?

A: In suitable conditions (open sky with sufficient satellite reception), if an RTK fixed solution (Fix) is obtained, you can expect about ±2 cm (±0.8 in) in horizontal position and about ±4 cm (±1.6 in) in height. Actual validations have shown differences of only a few millimeters (in all cases less than 5 mm (<0.20 in)) compared to professional surveying GPS, meaning accuracy that is practically imperceptible.

Q: How large an area can be measured at once when scanning point clouds with a smartphone?

A: The range for smartphone AR scans depends on the environment, but as a guideline you can continuously acquire point clouds ranging from tens of meters to hundreds of meters. Using LRTK Phone maintains positioning accuracy even when moving long distances, so, for example, you can walk along a slope about 200 m (656.2 ft) in length and scan it in 1–2 minutes. For very wide areas, you can divide the area and scan multiple times, then merge the data later.

Q: Do I need specialized knowledge or qualifications to use it?

A: No. Basic operations are completed within the smartphone app and are designed to be intuitive even without specialist knowledge. Simply attach the LRTK Phone to your smartphone and press the app’s start-positioning button; high-precision positioning begins automatically, and you can follow prompts to scan and measure. With a short training or by reading the manual, anyone on site can perform measurements with the precision of a surveyor.

Q: Can it be used indoors or where GPS signals are unavailable?

A: In indoor environments or tunnels where GNSS signals cannot be received, real-time high-precision RTK positioning will not function. In such cases, relative measurements using only the smartphone’s AR functions are possible, but absolute coordinate accuracy is not guaranteed. However, you can compensate by using a previously acquired control point to measure in a local coordinate frame, for example. The technology is most powerful in open outdoor environments, but by adjusting usage to the environment it can still be useful in various situations.

Q: Which smartphones are supported?

A: At present, the solution is for iPhone. In particular, iPhones equipped with a LiDAR scanner (models since iPhone 12 Pro) can fully utilize the AR point cloud scanning features. Expansion of supported devices is under consideration, but the latest iPhones can use LRTK Phone without issue. The app is available from the App Store, so if you have a compatible iPhone you can try high-precision positioning right away.